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【目的】新型隐球酵母是人类条件致病真菌,主要感染免疫缺陷患者。该酵母最显著的特征是细胞外包被着多糖荚膜,这一重要致病因子的调控机制复杂。本文研究旨在阐述编码铜依赖转录因子的CUF1基因对其荚膜生物合成的负调控作用。【方法】以野生型菌株为对照,对CUF1缺失的突变菌株进行菌落形态观察、荚膜墨汁染色的显微观察、细胞聚沉试验以及荚膜定量分析。【结果】与野生型菌株相比,Δcuf1突变株产生的菌落更粘,显微镜下亦可明显观察到荚膜更厚。同样数量的细胞,突变株聚沉平衡后体积更大。此外,荚膜粗提物定量称重分析也证明突变株产生了更多的荚膜。并且外源铁可以回复Δcuf1突变株荚膜过量产生的表型。【结论】铜应答转录因子1(Cuf1)对荚膜的生物合成具有负调控作用。Cuf1可能通过铁的高亲和吸收途径调控铁吸收而实现该作用的。
【Objective】 Cryptococcus neoformans is a human pathogenic fungus that infects patients with immunodeficiency. The most prominent feature of this yeast is the extracellular coating of the polysaccharide capsule, and the regulatory mechanism of this important virulence factor is complex. The aim of this study is to elucidate the negative regulatory effect of CUF1 encoding copper-dependent transcription factor on its capsular biosynthesis. 【Method】 The wild-type strain was used as a control, and the mutant strain with CUF1 deletion was observed for colony morphology, microscopic observation of capsular ink stain, cell sedimentation test and capsule quantitative analysis. [Results] The colony produced by the Δcuf1 mutant was more viscous than the wild-type strain, and the capsule was apparently thicker under the microscope. The same number of cells, mutant strains after the balance of sedimentation greater volume. In addition, quantitative weighing analysis of capsular crude extracts also demonstrated that the mutant strains produced more capsular. And exogenous iron can recover the phenotype of the capsular overproduction of the Δcuf1 mutant strain. 【Conclusion】 Copper-responsive transcription factor 1 (Cuf1) has a negative regulatory effect on capsule biosynthesis. Cuf1 may do this by regulating iron absorption through the high-affinity iron absorption pathway.